Field of Endeavor
The present application relates to additive manufacturing, and more particularly to architected materials and structures to control shock output characteristics.
State of Technology
This section provides background information related to the present disclosure which is not necessarily prior art.
Current methods of shock initiation and control of the wavefront properties are limited by the manufacturing methods and materials available for specific types of processing (machining, pressing, extruding, etc.), however the desire for control over the output shock front of an energetic material and/or high explosive is for materials or devices that perform outside of capabilities currently available.
The output detonation front of a dense explosive material is affected by the edges of the geometry of the explosive part such that, during detonation through the material, the pressure front lags the bulk shock front of the material. This results in a parabolic or curved shock front through the cross section of the part. Many applications are not affected by the this difference in the arrival time of the shock front as a function of time, but some, including study of the fundamental behavior of energetic and non-energetic materials, are very much affected by this difference, and as such, alternative methods other than bulk explosive materials must be used, such as a plane wave generator, or a gas gun or propelled material to initiate the detonation or shock the material. Current plane wave generators are created using two different high explosives, machined into a geometry of a nested cone within a cylinder, and are then mated together. This requires very precise machining, as any gaps between the materials will result in a malformed shock front, and a very limited set of materials which may be used. On top of these technical hurdles, the output wave, which arrives in a linear fashion, does not have a uniform pressure profile. Gas gun techniques, while very effective and well understood, require specialized facilities, are normally only able to perform one experiment at a time, and are labor intensive. Both of these types of uniform initiation systems are not able to quickly, accurately, and arbitrarily deliver a shock front in a cost and time effective manner.
There have been ways to produce plane wave generators using HE materials, but they have:                a.) Only been made as a cylindrical, plane wave generator        b.) Have only been made with pressing, machining and joining        c.) Have only been made using a handful of HE materials        
These efforts have been very expensive ($50 k/each). They are rarely used due to their expense.
Previous methods of modifying the output characteristics of an energetic/HE bulk part could only achieve specific changes to the shock characteristics, such as the shock front arrival time as a function of radial distance. These parts are extremely difficult to machine and assemble, and resulted in a prohibitively expensive HE part that only has one type/shape of output. The other disadvantage of these systems is that only specific types of energetic materials fit all of the criteria needed to enable both the effects desired (difference in detonation speed, energy density, etc.) and the correct processing constraints (machining, pressing, etc.). With the inventors' additive manufacturing apparatus, systems, and methods, the available types of materials that can be used to manufacture an energetic part as well as the types of HE printed, giving complete control over the propagation and arrival behavior of the part after detonation.